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Undifferentiated thyroid cancer

Medullary thyroid cancer

The medullary cancer is initiated from the so-called C-cells of the thyroid gland and its characteristic feature is calcitonin production. Calcitonin is a hormone which reduces the calcium content of blood.
In 80-85 per cent of the cases it occurs sporadically, but in the other 15-20 per cent it shows familial accumulation. While the sporadic form usually develops as an isolated tumor, the inherited form has more foci. Sporadic forms appear very insidiously and by the time the diagnosis is set up, in almost 50 per cent of cases metastases are already present.
The prognosis of medullary cancer is worse than in case of the well-differentiated thyroid cancers, but it occurs less frequently: in 5-10 per cent of thyroid cancer cases.


Undifferentiated thyroid cancer: Anaplastic cancer

This is the most malignant thyroid cancer type. This cancer type is deriving from immature cells that are in an earlier stage of cell development. Mostly it occurs over the age of 60, grows rapidly and forms metastases intensively in other organs. It resists almost all treatments, even surgery. Within 6 months or within a year after setting up the diagnosis it is surely fatal. Not rarely a multi-nodular goiter can be found in the medical history of patients with anaplastic cancer. The malignantly transformed nodule is firm and it is attached to its environment.


FDG PET-CT in case of thyroid cancer

In case of papillary and follicular differentiated thyroid cancer types, PET-CT is especially useful in determining whether a recurrence or a distant metastasis has developed at the original site or not after surgery and radioiodine therapy. Performing the examination is especially recommended in cases where tumor marker level (thyroglobulin) in blood is increased, but the compulsorily performed whole body scintigraphy with iodine isotope is negative.
Similarly to the above mentioned, in case of medullary cancer PET-CT may also have an important role in finding a possible recurrence or distant metastasis after surgery, especially if levels of tumor markers (calcitonin, CEA) are increased.
PET-CT does not have substantive role in the diagnosis of thyroid cancers, in determining the primary stage, in the assessment of therapeutic response, in regular follow-up and in planning a radiation therapy.
If during a PET-CT examination –performed with another indication- an FDG-accumulating focus is found, further evaluation (ultrasound-guided fine-needle aspiration biopsy and cytology) is pronouncedly recommended, because in about 50% of these cases cytological examination indicates malignancies.